The current invention relates to a method for buffering thermal energy according to the preamble of the first claim.
The present invention also relates to a thermal energy buffer system for buffering thermal energy.
The present invention also relates to software for executing the method or for implementing the above system.
Methods for buffering thermal energy and thermal energy buffers are already known to the person skilled in the art. An example of a thermal energy buffer is for example a water heating unit of a domestic hot water system. Such a thermal energy buffer contains a thermal buffering medium, often water, contained in a tank and a controller controlling a heater of the thermal buffer. The heater can for example be an electrical heater provided at the bottom of the tank. In such water heating units, water often enters the tank at the bottom of the tank and exits the tank at the top. The controller is provided to receive a signal representing three signals representing thermal energy values related to the thermal energy buffer. These values purely represent temperatures and often are a minimum temperature, a maximum temperature and the temperature of the water in the tank measured by, for example, a sensor present in the tank at a certain location. When the temperature measured by the sensor drops below the minimum temperature, the controller activates the heater, for example until the maximum temperature is obtained. In such a configuration the minimum temperature represents the predetermined minimum amount of energy present in the thermal energy buffer.
However, such methods and corresponding water heating units can not be readily implemented in a so called smart-grid in which agents determine the functioning of the heater in function of energy price, amount of energy needed, flexibility of the energy consumption of the water heating unit, availability of renewable energy, etc.
Moreover, it has been found that when multiple water heating units of domestic hot water systems are for example controlled by a single controller using the thermal energy values provided by the different thermal energy buffers to the controller, the thermal energy values being expressed in, for example, degrees Celsius, controlling the water heating units in a consistent way such that the amount of energy of the different water heating units can be compared is not easy as the different thermal energy values are determined for different water heating units having different volumes for the tank, have different positions of the sensor sensing the temperature of the water in the waterheating unit, etc.
Although domestic water boilers of a complete population consume a great deal of energy and hence could contribute to maintaining stable network values if properly controlled, little progress has been made in coordinating the switching of these boilers other than to switch them on at night to make use of a night tariff. Any network connections at domestic premises are a potential security threat as they become easily accessible. It is not obvious how to improve this situation.